The water-soluble derivatives of carbon microspheres were prepared by L-cysteine which was very important to human *** microspheres(CMS)were synthesized by chemical vapor deposition method(CVD)using acetylene as carbo...
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The water-soluble derivatives of carbon microspheres were prepared by L-cysteine which was very important to human *** microspheres(CMS)were synthesized by chemical vapor deposition method(CVD)using acetylene as carbon source,argon as carrier gas and ferrocene as *** the CMS were treated with nitrate and chemically modified with
First-principles calculations were performed to investigate the heat of formation, elastic constant and density of states of transition metal dinitrides TMN2(TM = Hf, Ta, W, Re, Os, Ir, Pt and Au) in P21/c space group...
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First-principles calculations were performed to investigate the heat of formation, elastic constant and density of states of transition metal dinitrides TMN2(TM = Hf, Ta, W, Re, Os, Ir, Pt and Au) in P21/c space group. Our calculation results indicate that HfN2, TaN2, ReN2, OsN2, IrN2and PtN2are thermodynamically and mechanically stable. Among them, OsN2has the highest bulk modulus (418GPa) and shear modulus (257GPa). Significant hybridization between TM5d and N2p can be seen from DOS and PDOS.
Oriented carbon films with novel structure were prepared by microwave plasma from heavy oil residue. The prepared films were characterized by field emission scanning electron microscopy, high resolution transmission e...
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Oriented carbon films with novel structure were prepared by microwave plasma from heavy oil residue. The prepared films were characterized by field emission scanning electron microscopy, high resolution transmission electron microscopy, X-ray powder diffraction and Raman spectroscopy. The products were formed with high purity, and oriented as the shape of a strip-like wheat spike. The outer layers of the spike have a higher degree of crystallization, the maximum width and length are about 65 nm and 900 nm, respectively, while the central parts are amorphous. It was suggested that the products experienced a process from outer to inner growth. Some metals existed in the defiled asphalt, such as Ni and Fe, may contribute as catalyst to the aligned carbon film growth.
Al cladding layer on AZ31B magnesium substrate is created by a 5kW continuous wave CO2 laser melting the prior placed Al powder of which the pureness is 99.95%. OM and XRD were used to alalyse the microstructure, the ...
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Al cladding layer on AZ31B magnesium substrate is created by a 5kW continuous wave CO2 laser melting the prior placed Al powder of which the pureness is 99.95%. OM and XRD were used to alalyse the microstructure, the electrochemical corrosion, the micro-hardness and the abrasion performance are also tested with the microhardness instrument, the abrasion testing machine and the electrochemical corrosion equipment. The results show that: the Al cladding layer can combine with the substrate metallurgically, the microstructure of cladding layer becomes fine significantly, and the phase of the cladding layer are Al, Al17Mg12 and Al3Mg2. Micro-hardness of the cladding layer is 261~331HV0.1 which is improved 422~562% of that of the substrate. The furrows which are the typical character of abrasive wear appear on both the cladded layer and the as-recesived magnesium alloy. The wear loss of cladded layer is 31.43% of the as-received magnesium alloy. The wear resistance is improved by 68.57% correspondingly, and the average friction coefficient of the cladding layer is 0.058 lower than AZ31B substrate. The corrosion voltage of cladding layer is 1120mV, which increased 420mV compared to AZ31B magnesium substrate(698 mV), and the self corrosion was lower by one magnitude than AZ31B alloy.
Carbon microspheres were prepared from deoiled asphalt (DOA) by chemical vapor deposition (CVD). Furthermore, monodisperse Ni/C nanospheres were obtained by vacuum heat-treatment using the residue coke from previous e...
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Carbon microspheres were prepared from deoiled asphalt (DOA) by chemical vapor deposition (CVD). Furthermore, monodisperse Ni/C nanospheres were obtained by vacuum heat-treatment using the residue coke from previous experiment as carbon source and nickel powder as catalyst. The morphologies and structures of the products were characterized by field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD). Results showed that high purity and amorphous structure carbon microspheres with diameters ranging from 1-2 μm was achieved, that Ni/C nanospheres with size 10-30 nm exhibited obvious core-shell structures with nickel as cores and carbon as shells. Carbon shells surrounding the metal particles may offer excellent protection to the encapsulated metal nanomaterials.
A nanostructured surface layer was fabricated on a AZ91D magnesium alloy by using a high-energy shot peening(HESP).HESP induced structure along the depth of the treated sample surface layer was characterized by means ...
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A nanostructured surface layer was fabricated on a AZ91D magnesium alloy by using a high-energy shot peening(HESP).HESP induced structure along the depth of the treated sample surface layer was characterized by means of X-ray diffractometer (XRD),transmission electron microscope(TEM) and high resolution transmission electron microscope(HRTEM).The experimental results show that a deformed layer of about 50 μm has formed after HESP treatment and the average grain size increases from about 40 nm in the surface layer to about 200 nm at the depth of 40 μ*** surface nanocrystallization can realize intercoordination of the dislocations slipping and dynamic *** nanocrystalline grains have stacking faults and dislocation in their *** microhardness of the top surface is about triplicate that of the coarse-grained matrix.
The fatigue property of AZ31 magnesium alloy and its TIG welded joints were investigated. The ultrasonic peening treatment （UPT） was used to improve the fatigue property of the TIG welded joints, which was treated a...
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The fatigue property of AZ31 magnesium alloy and its TIG welded joints were investigated. The ultrasonic peening treatment （UPT） was used to improve the fatigue property of the TIG welded joints, which was treated at the weld toe by the UPT process. The test results show that the fatigue strength of the base metal of AZ31 magnesium alloys is 57.8 MPa, and those of the fillet joint and the transverse cross joint are respectively 20. 0 MPa and 17.2 MPa at 2 × 10^6 cycles. The fatigue strengths of two kinds of welded joints treated by the UPT are respectively 30. 3 MPa and 24. 7 MPa, which have been improved by 51.5% and 43.6%, respectively. The fatigue life of the fillet joint specimens is prolonged by about 2. 74 times and the fatigue life of the transverse cross joint specimens is prolonged by about 1.05 times when the stress range is at 40. 0 MPa.
Herein a higher purity 8-hydroxyquinoline organic metal complex, GaMq2Cl, was synthesized and purified by vacuum sublimation. Its structure, thermal stability and energy band structure were investigated by 1HNMR, elem...
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Herein a higher purity 8-hydroxyquinoline organic metal complex, GaMq2Cl, was synthesized and purified by vacuum sublimation. Its structure, thermal stability and energy band structure were investigated by 1HNMR, elemental analysis, TG analysis, UV-vis absorption spectra, fluorescent emission spectra and PL spectra. Experimental results show that the complex was a thermally stable material, with decomposition temperature being 348°C. GaMq2Cl consists of two 2-methyl-8-hydroxyquinoline ligands and one chlorin atom as well as one aluminum atom. Its UV absorption bands were at about 265 and 361 nm, its DMSO solution emitted intensive blue-green fluorescence at peak wavelength of 511 nm. The absorption band at about 265 nm can be assigned to π-π* of phenyl ring. Its optical gap was about 3.09 eV, as determined by intrinsic absorption band edge of the complex in DMSO solution. Under UV excitation at 365 nm, the complex in film emitted blue-green fluorescence with the maximum emission peak at 511 nm in PL spectra.
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